Deployment of FHIR-based IPF IHE consumer endpoints

Every project that exposes consumer endpoints of FHIR-based IHE components needs to configure a web application container for them. Currently the following containers have been tested:

• Standalone Apache Tomcat
• Embedded in Spring Boot

Neccessary configuration steps for all these variants will be described in corresponding sections below.

Standalone Apache Tomcat

To make the IPF application deployable in the Apache Tomcat servlet container, a deployment descriptor web.xml must include the FHIR servlet and servlet-mapping. With recent Servlet specifications, you can also put a corresponding web-fragments.xml file into the classpath.

Here is an example:

    <?xml version="1.0"?>
    <!DOCTYPE web-app PUBLIC "-//Sun Microsystems, Inc.//DTD Web Application 3.0//EN">

    <web-app>
        <display-name>Test IPF IHE Web-App</display-name>

        <!-- Servlet for FHIR  -->
        <servlet>
            <servlet-name>FhirServlet</servlet-name>
            <servlet-class>org.openehealth.ipf.commons.ihe.fhir.IpfFhirServlet</servlet-class>
            <!-- FHIR version to be used: DSTU3, R4 -->
            <init-param>
                <param-name>fhirVersion</param-name>
                <param-value>R4</param-value>
            </init-param>
            <init-param>
                <param-name>logging</param-name>
                <param-value>true</param-value>
            </init-param>
            <init-param>
                <param-name>highlight</param-name>
                <param-value>true</param-value>
            </init-param>
        </servlet>
    
        <!-- Camel Endpoint Resource Mapping, should be FhirServlet -->
        <servlet-mapping>
            <servlet-name>FhirServlet</servlet-name>
            <url-pattern>/fhir/*</url-pattern>
        </servlet-mapping>
    
    </web-app>

The following servlet init parameters are supported:

Parameter name	Type	Default value	Short description
fhirVersion	FhirVersionEnum	-	which FHIR version to be used: STU3 or R4
logging	Boolean	false	writes incoming requests into the log
highlight	Boolean	false	whether responses to requests from browsers are (syntax-)highlighted
pretty	Boolean	false	whether responses are indented
pagingProviderSize	Integer	50	amount of paging requests being maintained concurrently
defaultPageSize	Integer	20	default page size of returned resources
maximumPageSize	Integer	100	maximum page size of returned resources

A special case is the ITI-68 transaction. This is not a FHIR transaction as such but just a HTTP(S) download. Therefore, instead of being routed over the FhirServlet this transaction is served by a CamelServlet as provided by Camel’s Servlet component.

A web.xml snippet would look like this:

<servlet>
   <servlet-name>CamelServlet</servlet-name>
   <display-name>Camel Http Transport Servlet</display-name>
   <servlet-class>org.apache.camel.component.servlet.CamelHttpTransportServlet</servlet-class>
   <load-on-startup>1</load-on-startup>
 </servlet>

<servlet-mapping>
    <servlet-name>CamelServlet</servlet-name>
    <url-pattern>/binary/*</url-pattern>
</servlet-mapping>

The servlet definition above would match the following consumer endpoint:

   from("mhd-iti68://binary[?options]")

Embedded in Spring Boot

Container deployments embedded in Spring Boot can be easily achieved by depending on ipf-fhir-stu3-spring-boot-starter or and ipf-fhir-r4-spring-boot-starter. This starter module along with camel-servlet-starter sets up the necessary servlets and the servlet init parameters are mapped to application properties.

Note that Spring Boot supports Tomcat, Jetty and Undertow as servlet implementations.